Plenary: Next Frontier, Sunday, Afternoon Session
Presentation Authors: Caitlyn Harrison, Hong Song, Heying Duan, Guido A. Davidzon, Andrei Iagaru*, Stanford, CA
Introduction: 18F-DCFPyL is a radiolabeled ligand binding to prostate specific membrane antigen (PSMA), a recognized target for prostate cancer PET imaging. Through a research access program, 18F-DCFPyL PET/CT is available at our institution for patients with biochemical recurrent prostate cancer (BCR PC). We present our data from the use of 118F-DCFPyL in patients with BCR PC. We also show data from the comparison of 18F-DCFPyL PET/CT and 18F-NaF PET/CT for the detection of skeletal metastases.
Methods: We prospectively enrolled 50 participants (52-91 years old 71.2±7.4) who had 18F-DCFPyL PET/CT scans in the setting of rising prostate specific antigen (PSA) after definitive treatment with prostatectomy (31 patients) or radiation therapy (19 patients). Imaging started 60 minutes following administration of 9 mCi of 18F-DCFPyL. A total of 16 of the 50 patients (63-86 years old, 73.6±5.9 years) also had 18F-NaF PET/CT for identification of bone metastases. Up to 7 bone lesions were recorded per patient for each tracer.
Results: PSA values ranged from 0.23 to 698 ng/mL (mean±SD: 21.6±99.6) in this cohort. The observed 18F-DCFPyL PET/CT-positivity rate was 82% (41 positive scans and 9 negative scans). Uptake in the prostate bed was noted in 15 scans, in lymph nodes in 27 scans, in the skeleton in 19 scans, and in other visceral sites such as the lung, the adrenal gland and liver in 8 scans. Positivity rates were 47% (7/15) for PSA<1ng/mL, 100% (4/4) for PSA 1-2 ng/mL, 90% (9/10) for PSA 2-5 ng/mL, and 100% (21/21) for PSA >5 ng/mL. Putative sites of disease were detected with PSA as low as 0.4 ng/mL. Three patients did not have bone metastases. A total of 41 skeletal lesions were found. 18F DCFPyL PET/CT identified 32 bone lesions (78%) and 18F NaF PET/CT identified 35 lesions (85.4%). Congruent findings between 18F-DCFPyL and 18F NaF were found in 26/41 (63.4%) lesions. 18F DCFPyL identified 1 lesion missed on 18F NaF in 4 participants (4/41, 9.8%). However, 18F DCFPyL was negative in 2 patients with lesions found on 18F NaF (4/41 lesions, 9.8%). CT alone identified 21 lesions (51.2%). PSA velocity values were 16.59±42.50 ng/ml/year (range: 0.18-140.3) in patients with positive 18F-DCFPyL PET scans and 0.72±1.17 ng/ml/year (range: 0.05-3.76) in patients with negative 18F-DCFPyL PET scans.
Conclusions: 18F-DCFPyL uptake in multiple areas compatible with BCR PC suggests that 18F- DCFPyL PET localizes disease in a large proportion of patients, including at very low PSA values. In addition, 18F DCFPyL PET/CT had similar performance to 18F NaF PET/CT for detecting bone metastases. Taken together, 18F DCFPyL PET/CT may be used as a "one stop shop" for evaluation of patients with BCR PC. However, more patients have to be evaluated to support these findings.
Source of Funding: Prostate Cancer Foundation